Resistant hypertension--its identification and epidemiology.

Resistant hypertension is currently defined as the failure to achieve a goal blood pressure <140/90 mmHg in patients who are compliant with maximal tolerated doses of a minimum of three antihypertensive drugs, one of which must be a diuretic. The increasing prevalence of obesity and hypertension in the general population mean that this disorder has gained attention in the past decade. In the past 2 years, large-scale population-based studies such as the US National Health and Nutrition Examination Survey (NHANES) have specifically examined the prevalence and incidence of resistant hypertension, and associated risk factors. The findings suggest the prevalence of resistant hypertension is 8-12% of adult patients with hypertension (6-9 million people). The increasing prevalence of resistant hypertension contrasts with the improvement in blood pressure control rates during the same period. Studies also show that patients with resistant hypertension aged >55 years, of black ethnicity, with high BMI, diabetes or chronic kidney disease have an increased risk of cardiovascular events compared to nonresistant hypertensive patients. Analyses that exclude the effects of white-coat hypertension and pseudoresistant hypertension are also needed to clarify the epidemiology of true resistant hypertension.